Semester

Fall

Date of Graduation

2004

Document Type

Dissertation

Degree Type

PhD

College

Eberly College of Arts and Sciences

Department

Physics and Astronomy

Committee Chair

Leonardo Golubovic.

Abstract

We present unified theory of the far-from-equilibrium interfacial phenomena occurring in the multilayer homoepitaxial growth and erosion on (110) and (100) crystal surfaces. Within a unified model, here we elucidate the multitude of novel states on (110) and (100) surfaces as well as the transitions between them. In particular, by analytic arguments and numerical simulations, we address experimentally observed transitions between two types of rippled states on (110) surfaces. We discuss several intermediary interface states intervening, via consecutive transitions, between the two rippled states. One of the intermediary interface states, the Rhomboidal Pyramid State, was theoretically anticipated by us and subsequently seen by de Mongeot and coworkers in the epitaxial erosion of Cu(110) and Rh(110) surfaces. In addition, we find a number of interesting intermediary states having structural properties somewhere between those of rippled and pyramidal states. Prominent among them are the Rectangular Rippled states of long rooflike objects (huts) recently seen on Ag(110) surface. Also, we predict existence of striking interfacial structures that, unusually, carry persistent surface currents. These so called Buckled Rippled interface states are far-from-equilibrium relatives of the Abrikosov vortex state in type-II superconductors. We discuss the mechanisms of the coarsening growth of the multitude of the interfacial states on (110) crystal surfaces. The coarsening of the common rippled states on (110) surfaces is shown to be mediated by ensembles of climbing dislocations destroying perfect periodic order (coherence) of these growing structures. We also discuss the experimentally observed enhanced coarsening of the Rhomboidal Pyramid state intervening between the two rippled states. Finally, the general phenomenology of multilayer epitaxial growth and erosion on square (001) symmetry crystal surfaces and elucidate recently observed 45 degree rotation transition between pyramidal states on (110) surfaces. We predict and characterize novel intermediary states of many-sided pyramids ubiquitously intervening in these transitions and causing an enhanced roughening. We elucidate the actual effect of the vertical (pyramid-pit) growth asymmetry on the multitude of states on (100) and (110) crystal surfaces.

Download

Share

COinS